1. Field of the Invention
This invention relates to devices and methods for simultaneously observing a transparent object from two directions.
2. Description of the Prior Art
Heretofore, a transparent object, such as the junction of the cores or clads of two optical fibers, has been observed from two directions (e.g., horizontal and vertical directions) at the same time by using a microscope. As shown in FIG. 1, a reflector 2 is arranged in the optical path of an illuminating light beam 1 in such a manner that reflector 2 is inclined with respect to the optical path. A microscope 4 is arranged in the direction of light reflected by reflector 2. A transparent object 5 to be observed is positioned at the intersection of illuminating light beam 1 and reflected light beam 3A, so that the objective image and the objective reflection image of object 5 are observed through an objective lens 6.
In observing object 5 in two directions, the length of the optical path of the light beam, which passes through object 5 horizontally (in the X-direction in FIG. 1) and is then reflected by reflector 2 to reach objective lens 6, is different by as much as .delta. from the length of the optical path of the light beam, which is reflected by reflector 2 and then passes through object 5 vertically (in the Y-direction in FIG. 1) to reach objective lens 6. Accordingly, as shown in FIG. 2, the objective image, in the Y-direction, of object 5 is formed at 5', while the objective image, in the X-direction, of object 5 (namely, an objective reflection image) is formed at 5". The image forming position of the former image is different from that of the latter image as much as the following value: EQU .DELTA.=.delta..beta..sub.0.sup.2
The image forming position difference .DELTA. is approximately as follows: If the object and the reflector provide an optical path difference .delta. of 200 m.mu. (.delta.=200 m.mu.), objective lenses magnifications .mu..sub.0 of 5, 10 and 100 result in image forming position differences .DELTA. of 5 mm, 20 mm and 2 m, respectively. Accordingly, it is difficult to simultaneously observe the two images of the object with a single objective lens 6. Therefore, in the conventional method described above, it is necessary to move the objective lens of the microscope up and down to observe each of the two images clearly.
Thus, the above-described method is disadvantageous in the following points: The simultaneous observation of an object in two directions is considerably low in work efficiency. Furthermore, when it is required to handle the eccentricity or alignment of the axis of an optical fiber by using a TV monitor and a computer, each of the images in the two directions must be processed separately; that is, the required computer operation cannot be achieved in one action.